Answer=$56 for 25 gallons
$56 for 25 gallons vs. $32.05 for 15 gallons
to solve for this, simply divide the price by the number of gallons, so...
$56/25=$2.24 per gallon
$32.05/15=$2.14 per gallon
Now that we have the price per gallon, it is easy to see that $56 for 25 gallons is the better deal.